Recording process using quinolin-2-one or quinolin-4-one organic photoconductive substances

ABSTRACT

Electrophotographic recording process wherein a pattern of increased conductivity is produced image-wise in a photoconductive insulating recording layer using as the essential photoconductive compound guinolin-2-one, quinolin-4-one, certain analogs and structural derivatives thereof, as well as the bis forms thereof, dispersed in an insulating binder. At least about 10 percent by weight of the recording element is constituted by the photoconductive compound and a spectral sensitizing agent for the photoconductor can be included. This class of photoconductors is also useful in the production of phosphor patterns on cathoderay tube screens.

O United States Patent [151 3,660,084

Vanheertum et al. May 2, 1972 [54] RECORDING PROCESS USING ReferencesCited QUINOLIN-Z-ONE 0R QUINOLIN-4-ONE UNITED STATES PATENTS ORGANICPHOTOCONDUCTIVE Rlttel' 3,316,087 4/1967 Munder et al. [72] Inventors:Johannes Joseph Vanheertum, Halle-Zand- 3,475,169 10/1969 Lange ..96/1

hoven;'Albert Lucien Poot, Kontich; Jozef Frans wm w wilhelmus FOREIGNPATENTS OR APPLICATIONS Janssens, Aarschot, all of Belgium 788,8927/1968 Canada [73] Assignee: Gevaert-AGFA N.V., Mortsel, Belgium PrimaryExaminerGe0rge F. Lesmes [221 Flled: AssistantExaminerJohn c. Cooper,111 21 AppL 22,376 Attorney-William J. Daniel 57 ABSTRACT [30] ForeignApplication Priority Data 1 Electrophotographic recording processwherein a pattern of 5; Great i i "l increased conductivity is producedimage-wise in a photocon- Great Bmam 2961/69 ductive insulatingrecording layer using as the essential photoconductive compoundguinolin-Z-one, quinolin-4-one, [52] 25 3 certain analogs and structuralderivatives thereof, as well as 260/287 260/288 260/289 the bis formsthereof, dispersed in an insulating binder. At [51] Int Cl 3 5/06 leastabout 10 percent by weight of the recording element is [58] Fie'ld 5constituted by the photoconductive compound and a spectral sensitizingagent for the photoconductor can be included. This class ofphotoconductors is also useful in the production of phosphor patterns oncathode-ray tube screens.

33 Claims, N0 Drawings RECORDING PROCESS USING QUINOLIN-Z-ONE ORQUINOLlN-4-ONE ORGANIC PHOTOCONDUCTIVE SUBSTANCES The present inventionrelates to recording and reproduction of information-wise modulatedelectromagnetic radiation and to recording materials applied therefor.More particularly the present invention relates to a photographicrecording process utilizing the property of photoconduction ofsubstances as described herein.

A recording element having photoconductive properties and a sufficientinsulating power in non-irradiated state can be used for the productionof an electrostatic image.

Electrophotographic materials comprising a support and a photoconductivelayer containing .an inorganic or organic photoconductor, e.g. selenium,zinc oxide, anthracene, and particular heterocyclic compounds, are wellknown.

In the production of opaque photoconductive layers generally inorganicphotoconductive substances are used, while for preparing transparentphotoconductive layers mostly organic photoconductors are applied.

One of the important problems in the production of transparentphotoconductive layers is to find organic photoconductive substancesthat have a photosensitivity comparable with that of commonly usedinorganic photoconductive substances and that are easily spectrallysensitizable over the whole visible spectrum range.

An object of the present invention is the use in electrophotographicrecording materials of organic compounds that are photoconductive andare easily spectrally sensitizable.

group wherein R" and R" each represents hydrogen, an alkyl groupincluding a substituted alkyl group, an aralkyl group including asubstituted aralkyl group, a cycloakyl group including a substitutedcycloalkyl group, an aryl group including a substituted aryl group, anacyl group including a carboxylic acid acyl and sulphonic acid acylgroup both either or not in substituted form, a carbamoyl group(CONl-l,) or a substituted carbamoyl group,

Z represents the necessary atoms making part of a carbon chain thatcloses the nitrogen-containing heterocyclic ring including such ring insubstituted form and such ring that makes part of a fused ring system,

n is one or two.

The present invention includes also the use in a recording andreproduction process of the tautomeric structures of said compounds.Tautomeric structures are derived from said compounds wherein Rrepresents hydrogen.

Compounds within the scope of said general formula and that are suitablefor use according to the present invention are photoconductive compoundsof the quinolin-Z-one and quinolin-4-one series and compoundsstructurally derived therefrom wherein the oxygen atom in the 2-one and4-one group is substituted with a sulphur atom, a dicyanomethylenegroup, an imino group including an imino group substituted with acarbocyclic or heterocyclic radical of aromatic nature, an oxime group,a hydrazone group or a substituted hydrazone group.

Representatives of said quinolin-Z-one and quinoline-4-one compounds andstructural derivatives thereof are within the It is another object ofthe present invention to use such elec- L scope of the followingstructural formulae (A) and (B):

trophotographic recording materials in photographic recording processesaccording to which an electrostatic image is formed.

It is still another object of the present invention to providetransparent and semitransparent photoconductive recording elements ofparticularly high photosensitivity in the ultraviolet range as well asin the visible spectrum range.

Other objects and advantages of the present invention will becomeapparent from the description but are not limitative for the use of thedefined compounds in electrophotographic recording and reproductionprocesses.

According to the recording process of the present invention a pattern ofincreased conductivity is produced in a photoconductive insulatingrecording element containing a heterocyclic organic photoconductivecompound having the following structural formula:

I mm RiI"I(L1= 2)n-1 i wherein:

L and L each represents a methine group including a substituted methinegroup or a carbon atom that makes part of a homocyclic ring, e.g. abenzene ring including a substituted homocyclic ring,

R represents hydrogen, a hydrocarbon group including a substitutedhydrocarbon group, e.g. an alkyl group, an aralkyl group, a cycloalkylgroup, and an aryl group including said groups in substituted form,

X is an electronegative (electron-attracting) substituent e.g. oxygen,sulphur, an imino group including an imino group substituted with acarbocyclic or heterocyclic radical of aromatic nature, a

GN group, an oxime group, particularly a NOR group wherein v R ishydrogen or an aliphatic group, e.g. an alkyl group, or a hydrazonegroup or a substituted hydrazone group particularly a /RII III: (B) R1group, an oxime group, particularly a NOR group wherein R is hydrogen oran alkyl group, or a hydrazone group or a substituted hydrazone groupparticularly a group, and R" and R each represents hydrogen, an alkylgroup including a substituted alkyl group, an aralkyl group including asubstituted aralkyl group, a cycloalkyl group including a substitutedcycloalkyl group, an aryl group including a.

substituted aryl group, an acyl group including a carboxylic acid acyland sulphonic acid acyl group either or not in substituted form, acarbamoyl group (CONH,) or a substituted carbamoyl group,

Z represents the necessary atoms making part of a carbon chain thatcloses the nitrogen-containing heterocyclic ring including such ring insubstituted fonn and such ring that makes part of a fused ring system;examples of substituents for the ring closed by Z are alkyl, e.g.methyl, substituted alkyl e.g. trifluoromethyl, halogen e.g. chlorineand fluorine, an amino group, a substituted amino group e.g. adialkylamino group, a hydroxyl group, an alkoxyl group e.g. a methoxygroup, a carbamoyl group, a substituted carbamoyl group e.g. a CONHCl-igroup, an aminoacyl group e.g. a NHCC H, group, a sulphamoyl group, aN-substituted sulphamoyl group e.g. a --SO N(CH group, asulphonylfluoride group, a car bonylalkoxy group e. g. a carbethoxygroup,

R represents hydrogen, a hydrocarbon group including a substitutedhydrocarbon group, e. g. an alkyl group including a substituted alkylgroup e.g. a C C alkyl group, an aralkyl group including a substitutedaralkyl group, a cycloalkyl group including a substituted cycloalkylgroup, an aryl group including a substituted aryl group, an ester groupe.g. a carbonylal- I koxy group such as a carbethoxy group, a carbamoylgroup including a substituted carbamoyl group, an amino group includinga substituted amino group,

R represents hydrogen, a hydrocarbon group including a substitutedhydrocarbon group e.g. an alkyl group including a substituted alkylgroup e.g. a C -C alkyl group, an aralkyl group including a substitutedaralkyl group, a cycloalkyl group including a substituted cycloalkylgroup, an aryl group including a substituted aryl group, a carboxylicacid group, an ester group e.g. a carbonylalkoxy group such as acarbethoxy group, or a carbarnoyl group including a substitutedcarbamoyl group, and

R and R together represent the necessary atoms to close a homocyclicring including such ring in substituted form or making part of a fusedring system.

Compounds according to the above general formulae that are suitable foruse in the manufacture of an electrophotographic recording materialaccording to the present invention are listed in the following Tables I,II and III. In Table III duplo structures are exemplified.

Said heterocyclic compounds, e.g. those containing the quinolin-2- or4-one ring system can be introduced into a polymeric chain by knownmethods, e.g. by introducing in said i system an a,B-ethylenicallyunsaturated group and by applying a subsequent proper ionic or radicalpolymerization, or by linking said ring system to an already existingpolymer chain by means of an addition or substitution reaction, e.g. byusing polyvinylbenzyl chloride whose chlorine atoms have beensubstituted with an active hydrogen atom of the quinolin-2- orquinolin-4- compounds.

Polymers containing heterocyclic organic systems for the purpose of thepresent invention have not to be of a high molecular weight in order toobtain a practical useful photoconductivity.

The photoconductive heterocyclic compounds used according to the presentinvention are prepared according to methods known per se. As anillustration of the preparation of quinolin-Z-one compounds, also calledcarbostyril compounds, reference is made to the published Dutch Pat.Specification No. 6,603,985 filed Mar. 25, 1966 by Farbenfabriken BayerAG. corresponding with the Canadian Pat. Specification No. 788,892 filedMar. 24, 1966 by Farbenfabriken Bayer AG.

The preparation of particular quinolin-4-one compounds is described,e.g., in the French Pat. Specification No. 1,202,105 filed June 14, 1956by Badische Anilin- & Soda-Fabrik A.G., Chem. Abstracts 61 (1964) 10657e, J.Org.Chem. 23 (1958) 762-763, and J.Prakt.Chem. I 7 (1962) 135-146.

Preferred photoconductive compounds are quinoline compounds, thatcontain the above indicated value for X and an electron-donating(electron-rich) substituent e.g. a hydroxy, amino, alkyl substitutedamino, alkoxy or alkyl group. In preferred compounds a dialkylaminogroup is present as a substituent on the aromatic ring part of thequinolin-Z-one or quinolin-4-one compound, or photoconductivederivatives thereof. The quinolin-2-one and quinolin-4-one compounds arefurther preferably substituted in the o-position to the X substituentwith a substituent having an aromatic character, e.g. a phenyl group ora substituent having an electronwithdrawing character such as a nitrogroup. For substituents TABLE I Melting point,

Number I I I I I I I l I I I l l I I l I I I I l l I I I I I I I I l l II I I I I I I l I I I I I I I I I I I I I I I I I I I I I I I I I l I II I I I I I I I I I I I I I I I I I I I I I I I I I I I I l I I I I I II I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I II l I I I I I l I I I I I I I I I I I I I I I I I I I I I I I I I I I II I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I II I I I I I I I I I I l I I I I l I I I I I I I I I I I I I I I I I I Il I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I II IIIII I I I I I I I I I I I I I I I I I I I I I I I I I l I I I I I II I I I I I I I I I I I I I I I I I I IIIII I I I I I I I I I I I I I II I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I II I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I II I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I l II l I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I II I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I II I I I I l I I I I I I I I I I I I I I I I I I IIIII zit-.255

CeH

mHO 2 2 mm m m 5 0 m m 2 10% &0 m n O 2% 05m 2 2 2 EoQ A y $0 m m m m 2Q m2 o onawwoflaw 1.2... n m mmc nmo mm n mmv c: 5 0522 2 00 m n G 50 @N83 506wmz2 m m 0520 m m 50 x 3 8 m m m m m 6% 2 5m 0 l E 2 m m m m m 28E 8 m m 200 m m EQW Q 50 3 s 5 m m 05m m n O 8 83 28.2.. m m 50 m m235G 8H m 2 13 m m m Hm HHWHWMH H n 56 E E m n mfin 2 5 0 "m0 2g 3 m m 22 2 2 2 2 2 m 50 2 m2 fifii fi w m m -ifiovzm 2 m 2 2 m 56 50 M:

8H m o owmz z E0 m m H H H H H EO 2 03A o E0 m 2 o 3N o E0 m 2 a? o $8 Gm a 2: o m m m 2222222 m m 5 0 a N E i m SH SH S Sm 59:52 $500 des n-803I2 02 O v m mm mm mm IIQZEQ wd m flO 0m wwm HHOZ E m mm n i Q mo aw 259%8" 8- m m m ow m m 2580 .........E0 8 m2 3 m umow m m 5 0 E6 2 own I. 0m mm 10w Hm mm mo wm 5 0 \ZT OO ma w HH m mm n mm H1O mO 2 an" 6' m m 'HOm mm MH O -Q ma m i. HHU

an I 1 u m mm mm 1 m "HMO 9 ma .leboammwawm HH mm n I. mm AEQO mm .1. mUm* 52 6 580 8H W O OWHMZ Z m mm Hm Hm m QmU "awn- \Z O m 0 wiZ Z mafia""m0 mm m Hfl Om n mm M H O mO 0w ESTO EBo mam. w m mm Hm mm m mo am ":0mzoo 02A, w m Hm m ":0 mO mn 5o Q O ESQ 05 w 5 m. HH m mm 29 2" ca w mmmm HH HH mo l wm EN iomvl E n MH UOOO HH mm m o HHU mm 00m. fi Hm mUmzOon HH E O mO v 0 a M 3H 3H m Sm m SW i 82:52 509 TABLE} II H-CH=CH-'CH=CH- I S. 133 =N-NHCOOCH3 159 =N-NHSOz- =N--NHSOgCnH;a 109vSame as above 122 127 =N-NH-,S CH

2 CH3.. H CuHaL; HJLH... H IL... =N-NHCONH2 160 21..." CaHs H.; CH3H..1H H 11.... Z12

=N-NHSO CH:

22..-" c5115."; H CH3 H.; H HI. B...- :25

=N-NHCO 23"... CH H HQ; H H; H.... 250

\ NH? =N-NHSO NHCOCH;

Mn." C 3 H CH3. H.. C11 0... H. H.... :N-NHg 1 25...... CH: H CH L. H H1-1.... 2 5

=N-NH s 0 -0H3,

26"-.- CH1 H CH HQ. H CH; 1-1...- CN 21 CH;' CN

H'...CH5' H... 207 116 H; H Hie 120 H.. (C2H5):- H; 112 H H; CH 11.. C H

CHL. H

TABLE III 7 H Sameasabove H Same as above,. H do with electron-donatingan electron-withdrawing character reference is made to Peter Sykes, AGuidebook to Mechanism in Organic Chemistry Longmans, London (1963) p.106-107.

Such preferred compounds are e.g. l-ethyl-3phenyl-7-dimethylamino-quinolin-Z-one, l-ethyl-3phenyl-7-diethylamino-quinolin-Z-one and which are also called 1-ethyl-3-phenyl-7-dimethylaminocarbostyril and l-ethyl-3-phenyl-7-diethylaminocarbostyril respectively. The former compound can,e.g., be prepared as follows, the parts being by weight:

17.9 parts of 2-ethylamino-4-nitroltoluene, 16.2 parts ofphenylglyoxylic acid ethyl ester, and 2 parts of pipcridine are heatedfor 8 hours to 200 C with stirring.

18 parts of the resulting 1-ethyl-3-phenyl-7-nitrocarbostyril in amixture of 50 parts of alcohol and 50 parts of concentrated hydrochloricacid are heated on a waterbath. A solution of 50 parts of tin(ll)chloride in 100 parts of concentrated hydrochloric acid is added to themixture with stirring. Stirring is continued for 1 hour, whereupon themixture is allowed to cool. The resultingl-ethyl-3-phenyl-7-aminocarbostyril is filtered ofl, boiled out with 200parts of 5 percent aqueous solution of sodium hydroxide, filtered whilehot, dried, and recrystallized from xylene. From the resultingl-ethyl-3-phenyl-7-aminocarbostyril(melting point: l70-l72 C) 13.2 partsare dissolved in 150 parts of dioxane. To the solution are added partsof percent solution of formaldehyde in methanol and 10 parts of Raneynickel. The mixture is heated for 4 hours to 1 10 C in an autoclave witha hydrogen pressure of 1 l0 atrn. Subsequently, the Raney nickel isisolated and the dioxan is distilled in vacuo. After recrystallizationfrom cyclohexane l-ethyl-3-phenyl-7-dimethylaminocarbostyril isobtained. Melting point: l09-l 12 C.

The following products listed with their respective melting point areprepared in an analogous way by a condensation reaction of the proper2-amino-4-nitrotoluene and phenylglyoxylic acid ethyl ester.

3-phenyl-7-dirnethylaminocarbostyril (258-262 C),lrnethyl-3-phenyl-7-aminocarbostyril (l90l92 C), l-

methyl-3-phenyl7-dimethylaminocarbostyril (l-l73 C),

l-methyl-3-(4'-methylphenyl)-7-dimethylaminocarbostyril 6o (l-90 C),l-methyl-3-(4'-methylphenyl) 6-methyl-7- dimethylaminocarbostyril(152-153 C), l-methyl-3-(3,5- dimethylphenyl)-7-dimethylaminocarbostyril(l5 l-153 C), l-ethyl-3-( 3 '-chlorophenyl)-7-dimethyl-aminocarbostyril(l6l-62 C), l-ethyl-3-phenyl-7-monoethylaminocarbostyril (l78-l 80 C),l-ethyl-3-phenyl-7-N-methyl-N- ethylarninocarbostyril (75-78 C).

In the resulting nitrocarbostyrils the nitro group is reduced to anamino group, which for the purpose of the present inven- 70 tionpreferably is alkylated.

The alkylation for preparing l-ethyl-3-phenyl-7-diethylarninoquinolin-2-oncpreferably is carried out as fol- I lows:

hours on an oil-bath at C.

79.2 g (0.3 mole) of l-ethyl-3-phenyl-7-amino-quinolin-2:1 v 75 one and109 g (0.6 mole) of triethyl phosphite are heated for 3 5 The reactionmixture is poured into 1 l of water and the whole composition isalkalized by means of a N aqueous sodium hydroxide solution. Theresulting precipitate is isolated and dissolved in 300 ml of warmacetone. A cooling 75.5 g of purifiedI-ethyl-3-phenyl-7-diethylamino-quinoline-2-one precipitated. Meltingpoint: 1 C (yield: 78 percent).

As an example illustrative for the preparation of a quinoline-4-one thepreparation of the compound 8 of Table I is given hereinafter.

This compound was prepared as follows. A mixture of 26 g of methyl esterof p-fluorosulphonyl-benzoylacetic acid, 21.2 g of p-benzoylamidoaniline, 300 ml of chloroform and 1 ml of strong hydrochloric acid wasrefluxed for 8 days with a separator in order to remove the water formedin the reaction mixture. The precipitate formed was filtered off and thechloroform removed by evaporation in vacuum. The reaction product havingthe following structural formula:

was isolated as an oily residue.

, This residue was added dropwise to 300 ml of boiling (250 C) DIPHY L(trade name of Farbenfabriken Bayer AG, Leverkusen, W. Germany, for amixture consisting of 27 percent by weight of diphenyl and 73 percent byweight of diphenyl oxide). The reaction mass was maintained for 5minutes at the boiling temperature of DIPHYL (250 C) while methanol wasdistilled. Then the reaction mass was cooled. The precipitate formed wasfiltered with suction, washed with methanol and ether and dried. Yield:10.5 g of compound 8 of Table I. Melting point: above 260 C.

As an example illustrative for the preparation of duplo" compoundslisted in Table III the preparation of compounds 5 and l l of said tableis given hereinafter.

Preparation of compound 5 of Table III g (0.1 mole) of4,4'-diamino-diphenyl oxide and 52 g (0.2 mole) of methyl ester ofp-fluorosulphonyl-benzoylacetic acid were melted together, whereupon 5 gof polyphosphoric acid as water-attracting product were gradually addedthereto while stirring.

The reaction mixture was maintained for 10 days at 50 C under vacuumconditions and kept away from contact with moisture from outside bymeans of a trap containing concentrated sulphuric acid. Thereupon thereaction mass was stirred into chloroform and filtered. The chloroformsolution obtained was washed with water and dried on anhydrous sodiumsulphate. The chloroform was removed by evaporation in vacuum. Theresidual product having the following structural formula:

SOzF

SOQF

was separated in the form of an oil.

This oil was added dropwise to 400 ml of boiling DIPHYL (trade name).The reaction mass was maintained for 5 min. at the boiling temperatureof DIPHYL (trade name) with stirring, and then cooled till 20 C. Theprecipitate formed was filtered with suction, washed with methanol andether, and dried. Yiled: 7.l g of compound 5 of Table III. Meltingpoint: above 260 C.

Preparation of compound 1 1 of Table In A mixture of 25.7 g (0.1 mole)of the hydrochloric acid salt I of 4,4'-diamino-diphenyl and 54.8 g (0.2mole) of ethyl ester of fluorosulphonyl benzoylacetic acid, 13.2 g (0.19mole) of waterfree sodium acetate and 150 ml of chloroform were refluxedfor 7 days. Then the chloroform was removed by evaporation under vacuum.The product having the following structural formula:

was separated oil. oil was added dropwise to 400 ml of DIPHYL (tradename). The reaction mass was maintained for 5 min. at the boilingtemperature of DIPHYL (trade name) with stirring and then cooled till 20C. The precipitate formed .was filtered with suction, boiled withacetonitrile, washed with methanol and ether, and dried. Yield: 10.2 gof compound ll of Table III.

Quinoline-Z compounds as described in Table II and wherein X is sulphurcan be prepared e. g. according to the following reaction scheme A:

The R, R, R and R substituents may have the significance of thecorresponding substituents of the general formula above Table II.

Equimolar amounts of ketoesterfl) and aromatic amine (II) are dissolvedin xylene contained in a distillation flash provided with afractionating column. The reaction mass is heated till the theoreticalamount of alcohol produced in the reaction is distilled off. Afterremoval of the solvent by evaporation the obtained product (III) ispurified by crystallization.

Product (III) is dissolved in concentrated sulphuric acid (1,350 ml permole) and the reaction mass after having been kept for 24 H. at roomtemperature is poured onto ice. The precipitate formed is isolated bysuction, washed with water, whereupon product (IV) is recrystallized.

Product (IV) is mixed with an equimolar amount of p-tolusulphonic acidalkyl ester and heated for to h. at about C. Thereupon the reaction massis treated with an aqueous lN sodium hydroxide solution. The precipitateformed is separated by suction and the obtained product V is purified bycrystallization.

This product is then dissolved in pyridine containing anexcess (1.2 moleper mole) of phosphorus pentasulphide and maintained at refluxtemperature for l to 3 h. After cooling the reaction mass is poured intowater, and the precipitate formed is separated by suction, and washed.The obtained product (VI) is purified by crystallization.

Compounds 10, l2, [4, 34 and 35 of Table II have been prepared that way.

Quinoline-Z compounds as described in Table II, and wherein X issulphur, can also be prepared according to the following reaction schemeB:

RI!!! RIII RCO ore-coon HI L-Q IIR'II Rl/I/ RI! R!!! l H2804 RC CH0 ()N(III) R/II R!!! I I N N 0 Pass s RI/I! I RI!!! RI] RI! The substituentsR, R, R", R' and R"" may have the same significance as the correspondingsubstituents exemplified in the structural formula above Table II.

The operating conditions are the same as explained for reaction scheme Aexcept for the alkylation reaction with ptolusulphonic acid alkyl ester.

The compounds ll, 13 and 36 of Table II were prepared that way.

Quinoline-4 compounds as described in Table I, and wherein X is sulphur,can be prepared according to the following reaction scheme C:

1'3 6 1 N N N @3 R1 I Q3 S W R2 (I) (II) (III) R 1 represents an alkyliodide e.g. methyl iodide.

According to said reaction scheme C, compound 16 of Table I was preparedas follows:

2-methyl-4-chloro-quinoline (I) was mixed with an excess of methyliodide(5 mole per mole) and the reaction mass was maintained at refluxtemperature for 35 h. Then the reaction mixture was washed with ether.

Compound (II) wherein R and R were both methyl was obtained in 67percent yield in the form of a crystalline product melting at 250 C.

This product was dissolved in dry ethanol (1,600 ml per mole) andmaintained at reflux temperature for 12 hours in admixture with anexcess of sodium hydrogen sulphide (3 moles per mole).

The reaction mass was filtered hot and cooled. Compound (III) (R, and R,being both methyl) crystallized, whereupon it was recrystallized fromethylene glycol monomethyl ether. Yield: 59 percent. Melting point: 224C.

The quinoline compounds wherein X is an oxime group can be preparedaccording to a known method for producing an oxirne, e.g. as describedby Vogel in Practical Organic Chemistry, 3rd Ed. Longmans, (1959) 741.

According to another method the reaction scheme D is followed:

Preparation of compound (II) 2-phenyl-4-chloro-quinoline is mixed withan excess (3 mole per sole) of dirnethyl sulphate and for 24 hoursheated at C. After cooling and washing with ether, the compound (II) isobtained in a quantitative yield. Melting point: 50 C. Preparation ofcompound (III) 0.02 mole of compound (II), 0.04 mole of sodium carbonateand 0.03 mole of hydroxylammonium chloride are dissolved in a mixture of50 ml of chloroform and 25 ml of methanol and refluxed with stirring for2 h. After cooling the precipitate is separated by suction and washedwith water. This washed precipitate consisting of compound (III) wascrystallized from ethylene glycol monomethyl ether. Yield: 50 percent.Melting point: 258 C.

The quinoline compounds wherein X is an imino group substituted with anaromatic group can be prepared according to known methods for producinga ketone anil, e. g. according to reaction scheme E as follows:

Ar-NH:

Compound II of reaction scheme D OH Ar is e.g. a phenyl group.

Preparation of compound (111) wherein Ar=phenyl. Equimolar amounts ofcompound (H) and aniline are dis solved in chloroform and refluxed for,4 h. Then the chloroform is evaporated under vacuum and the residue istreated with a 20 percent by weight aqueous solution of sodiumcarbonate. The solid product is separated by suction, washed and dried.The yield is quantitative. Melting point of compound (11! (Ar beingphenyl): l50 C.

The quinoline compounds wherein X is a hydrazone group can be preparedaccording to a known method for producing a hydrazone compound startingfrom a ketone.

Acyl-substituted hydrazone groups in the 2-position of quinoline can beintroduced according to preparation methods described in the U.K. Pat.Specification No. 993,749 filed July 30, 1962 by Gevaert Photo-ProductenN.V., the U.S. Pat. Nos. 3,245,787 issued Apr. 12, 1966 of Jozef FransWillems and ,Jan Jaeken and 3,293,032 issued Dec. 20, 1966 of Jan Jaekenand Maurice Antoine de Ramaix and the UK. Pat. ap-

plication Ser. No. 5979/69 filed Feb. 4, 1969 by Gevaert-Agfa N.V.

Acyl-substituted hydrazone groups in the 4-position of quin oline can beintroduced according to reaction scheme F:

17 /N\\ HzNNHCOR l l l COR 4J1 I lNH or SO R R represents a hydrocarbongroup or a heterocylic group which groups may be further substituted.Compound (I) together with an equimolar amount of R'CONHNH or R SO NHNHis refluxed in ethanol for 8 h.

Thereupon ethanol is removed by evaporation. The residue is dissolved inpyridine and min. later the obtained solution is poured into ater. Theprecipitate formed is separated by suction, washed with water, andcrystallized.

The compounds wherein X is a dicyanomethylene group can be prepared byallowing to react propane dinitrile with the appropriate heterocyclicquaternary salt having a methylmercapto group in ortho position to thequaternary nitrogen atom. The reaction conditions for such preparationcan be learned from the preparation ofN-isopropyl-4,7-dimethyl-quinoline- Z-dicyanomethylene.

3.4 g of N-isopropyl-2-methylmercapto-4,7-dimethylquinolinium iodidetogether with 1.2 g of propane dinitrile were dissolved in a mixture of30 ml of pyridine and 0.3 ml of piperidine. The reaction mixture is keptat C for 24 h. and thereupon poured into water.

The precipitate formed was filtered with suction, washed with water anddried. Melting point: 21 1 C. Yield: 2 g.

The photoconductive compounds applied according to the present inventionmay be used alone or in combination with substances imparting desiredchemical or physical properties to the recording element. So, thesesubstances can be combined with other substances, that either or not arephotoconductive and exert an influence e.g. on the dark-resistivity, thedischargeability or conductivity of the recording layer by an exposureto electromagnetic radiation, or on the transparency or the quality ofthe final image, e.g. by counteracting the fringe effect as described inthe U.K. Pat. Specification No. 1,007,349 filed Oct. 12, 1961 by GevaertPhoto-Producten N.V.

The photoconductive compounds used according to the present inventionare preferably applied in admixture with (a) compound(s) that cause(s)an increase of the general sensitivity and/or of the sensitivity toelectromagnetic rays of a particular part of the spectrum.

' Fringe effect occurs when large electrostatically charged areas aredeveloped and is characterized by the deposit of electrostaticallycharged substances only at the edges of said areas. In order to inhibitor to decrease said effective dispersable particles, e.g. inorganicpigment particles and organic water-insoluble particles, areincorporated into the continucaco 54.34 MgCO 45.15 F5203 0.04 A1203 0.03

5 and DRY-FLO (trade name of National Starch and Chemical Corporation,Plainsfield, N.J., U.S.A., for a starch ester containing hydrophobicgroups).

These particles size between 1 and 5 p. and are preferably used in anamount of 2.4 to 24 percent by weight in respect of the homogeneousphase material contained in the recording layer. Optimal results areobtained with an amount of 6 percent by weight.

A proper combination with selected binding agents and/or curing agentsmay result in an enhancement of the total sensitivity so that the binderor curing agent applied may be considered as a sensitizing agent.Preferably the recording layer contains at least 10 percent by weight ofthe photoconductive substance applied according to the presentinvention. The electrically insulating binding agent applied to ofl'erto the recording layer the desired mechanical strength preferably has aresistivity of at least 10 ohm/cm.

According to a particular embodiment the recording layer consists of thephotoconductor, which, e.g., is applied to a 25 suitable support inmolten state forming a microcrystalline or glass-like layer on cooling.This technique can be applied when the photoconductive recording elementhas not to possess a high mechanical strength. For such techniquereference is made to the Canadian Pat. Specification No. 712,541 filedFeb. 5, 1960 by Gevaert Photo-Producten N.V.

Macromolecular compounds suitable for use as insulating binding agentfor the photo-conductive compounds are, e.g., natural resins such asdammar resin, gum arable, microcrystalline waxes, modified naturalsubstances such as cellulose diacetate, cellulose triacetate, and ethylcellulose, pentaerythrite polyesters or modified colophony resins andester gums, polymerisates such as polyethylene, polystyrene andcopolymers of styrene, polyvinyl acetate and copolymers of vinylacetate, polyvinyl acetals of formaldehyde, acetaldehyde orbutyraldehyde, polyacrylic acid esters and polymethacrylic acid esters,coumarine-indene resins; and polycondensates such as glycerol-phthalateresins and other glyceryl polyesters, alkyd resins, diethylene glycolpolyesters, formaldehyde resins and silicone resins.

Preferred binding agents are halogen-containing polymers.

The preferred recording materials according to the present inventioncontain the organic photoconductive compounds in admixture with ahalogen-containing polymer. Such polymers and a sensitizing treatmenttherewith are described in the UK. Pat. Specification No. 964,878 filedMay 3, 1960 by Gevaert Photo-Producten N.V. According to saidspecification a material suitable for use in electro-photographycomprises a photoconductive layer incorporating an organic monomericphotoconductor and a halogen-containing polymer in such layer or in ajuxtaposed layer (if any), e sensitivity of said photoconductor havingbeen increased by making it to interact with said halogen-containingpolymer by heating.

In the following Table IV a list of preferred polymeric binding agentsis given, which may be used in combination with the heterocyclic organicphotoconductors of use according to the present invention as well as thecorresponding suitable solvents.

TABLE IV Polymeric binding agent defined by its structural unit(s)Sulveut CH3 Methylene chloride. :0 ).--0-01s- SO2 nn l C1 i Thephotoconductive compounds applied according to'the and polymeric organicphotoconductors, e.g. those described present invention can be used inadmixturewith otheriknown in the published Dutch 'Pat. application Ser.No. 6,901,214 photoconductive substances, e.g. sulphur, selenium, 7ofiled-181134, f gfa N-V- photoconductive oxides, sulphides; andselenides of zinc, cad- The inherent I 7 spectra] sensltlvr of ,most ofthe hotoconmercury mummy m and TINY 'cmbe ductive-compounds listed inTami- 5 I, n, and III-is mainly situused in combination with organicmonomeric photoconducand in th U v tors e.g. anthracene, anthraquinone;polymers 6011mm n g N- mm c near m the range of 360m to 420vinylcarbazole recurring units and other known monomeric It is possibleto increase or extend the spectral sensitivity of recording materialsaccording to the present invention in different ways, e.g. by addingso-cailed spectral sensitizing agents for the photoconductive substancescontained in the recording element or by admixing to the saidheterocyclic organic photoconductive compounds other photoconductivesubstances, the inherent sensitivity of which for a particular part ofthe electromagnetic radiation spectrum is higher than that of saidcompounds.

So, according to a special embodiment of the present inventionsemi-transparent recording layers are prepared, in which saidheterocyclic photoconductive compoundsare used in admixture with (an)inorganic photoconductive substance(s), especially photoconductivesubstances of the group of zinc oxide, photoconductive lead(ll) oxideand photoconductive cadmium sulphide.

So, for instance a small amount of an inorganic photoconductive compoundsuch as photoconductive zinc oxide (1.5 g) in respect of 4 g ofl-ethyl-3-phenyl-7-diethylaminoquinolin- 2-one ofiers an interestingsensitivity of the recording layer to ultra-violet radiation and allowsthe extension of the spectral sensitivity of both the heterocyclicorganic photoconductor and the inorganic photoconductive substances intothe visible part of the spectrum by means d same or difi'erentsensitizing dyestuffs.

Suitable spectral sensitizing dyestuffs for the organic photoconductorare among others organic dyestufis, known as methine dyes, or xanthenedyes of which the phthaleins and rhodamines are subclasses, andtriarylmethane dyes e.g. crystal violet (C.l. 42,555) and thetriarylmethane dyes described in published Dutch Pat. application Ser.No. 6,704,706 filed Apr. 3, 1967 by Gevaert-Agfa N.V. The term methinedyes includes monoas well as polymethine dyes which dyes are known tothose skilled in the art of the spectral sensitization oflight-sensitive silver halide. Preferred methine dyes are of thecationic type and preferably contain one, three, five or seven carbonatoms in straight line in the methine part linking up two heterocyclicnitrogen-containing nuclei of the methine dye. As preferred xanthenedyes Rhodamine B (C.l. 45,170), Rose Bengale (C.l. 45,440) andFluorescein (C.l. 45,350) are mentioned. The spectral sensitizing dyesare preferably added to the recording layer composition in a proportionof 0.01 to percent by weight in respect of the photoconductivesubstance(s).

Particularly preferred methine dyes are within the scope of thefollowing general formulae:

I. l a 4 halogen and alkoxy, a five or six membered heterocycle theheteroatom of which is oxygen, sulphur, selenium or nitrogen such as 2-,3-, or 4-pyridyl, 2-furyl, 2-thienyl, etc. including their quaternarysalts,

R, stands for hydrogen or has one of the meanings given for 1) R standsfor hydrogen, alkyl, alkoxy or halogen or together with R, forms analkylene bridge such as dirnethylenc and trimethylene,

each of R and R, (the same or different) stands for hydrogen, alkyl,alkoxy or halogen or together represent the atoms necessary to completea fused-on benzene nucleus; X represents an anion e.g. Cl, Br, 1', C10CH SO] or HzC-Q-SO'u,

and

Z represents the atoms necessary to complete a heterocyclic nucleus ofthe types used in the production of cyanine dyes e.g. such as those ofthe thiazole series e.g. thiazole, 4- methylthiazole,4-methyl-5-carbethoxythiazole, 4-phenylthiazole, S-methylthiazole,5-phenylthiazole, 4-(p-tolyl)- thiazole, 4-(p-bromophenyl)-thiazole,4,5-dimethylthiazole, 4,5-diphenylthiazole, 4-(2-thienyl)-thiazole,4-(m-nitrophenyl)-thiazole, those of the benzothiazole series, e.g.benzothiazole, 4-chlorobenz0thiazole, 5-chlorobenzothiazole,

6-chlorobenzothiazole, 7-chlorobenzothiazole, 4-methylbenzothiazole,S-methylbenzothiazole, 6-methylbenzothiazole, 5-bromobenzothiazole,6-bromobenzothiazole, 6-sulphobenzothiazole, 4-phenylbenzothiazole,S-phenylbenzothiazole, 4-methoxybenzothiazole, S-methoxybenzothiazole,-methoxybenzothiazole, 5- iodobenzothiazole, 6-iodobenzothiazole,4-ethoxybenzothiazole, S-ethoxybenzothiazole, 4,5,6,7-

tetrahydrobenzothiazole, 5,6-dimethoxybenzothiazole, 5,6-dioxymethylenebenzothiazole, 5-hydroxybenzothiazole, 6-hydroxybenzothiazole, 5,6-dimethylbenzothiazole, those of thenaphthothiazole series e.g. naphtho[2,l-d]thiazole, naphtho[1,2-d]thiazole, 5-methoxynaphtho[ l ,2-d]-thiazole, 5-ethoxynaphtho[l,2-d]-thiazole, 8-methoxynaphtho[ 2, l -d]- thiazole,7-methoxynaphtho[2,l-d]-thiazole, those of thethionaphtheno[7,6-d]-thiazole series e.g.7-methoxythionaphtheno[7,6-d]-thiazole, those of the thiadiazole seriese.g. 4-phenylthiadiazole, those of the oxazole series e.g.4-methyloxazole, S-methyloxazole, 4-phenyloxazole, 4,5- diphenyloxazole,4-ethyloxazole, 4,5-dimethyloxazole, 5- phenyloxazole, those of thebenzoxazole series e.g. benzoxazole, S-chlorobenzoxazole,S-methylbenzoxazole, S-phenylbenzoxazole, -methylbenzoxazole,5,6-dimethylbenzoxazole, 4,6-dimethylbenzoxazole, S-methoxybenzoxazole,6-methoxybenzoxazole, S-hyclroxybenzoxazole, 6-hydroxybenzoxazole, thoseof the naphthoxazole series, e.g. naphtho[2, l -d]oxazole,naphtho[l,2-d]oxazole, those of the selenazole serieseg. 4-methylselenazole, 4-phenylselenazole, those benzoselenazole series e.g.benzoselenazole, 5- chlorobenzoselenazole, S-methoxybenzoselenazole,S-methyl- 6-methoxybenzoselenazole, 5,6-dioxymethylenebenzoselenazole,5-hydroxybenzoselenazole, 4,5,6,7-tetrahydrobenzoselenazole, those ofthe pyrimidine series, those of the quinoxaline series, those of the,

quinazoline series, those of the l-phthalazine series, those of theZ-pyridine series e.g. pyridine, S-methylpyridine, 3- nitropyridine,those of the 3,3-dia1kylindolenine series e.g. 3,3-dimethylindolenine,3,3,5-trimethylindolenine, 3,3,7- trimethylindolenine, etc., those ofthe benzirnidazole series e.g. benzirnidazole,5,6-dichlorobenzimidazole, 5- chlorobenzimidazole,5,6-dibromobenzimidazole, 5-chloro-6- amino-benzimidazole,S-chloro-G-bromobenzimidazole, 5- phenylbenzimidazole,S-fluorobenzimidazole, 5,6-

difluorobenzimidazole, S-cyanobenzirnidazole, 5,6- dicyanobenzimidazole,-chloro6-cyanobenzirnidazole, 5-

fluoro-6-cyanobenzimidazole, 5-acetylbenzimidazole, 5-chloro-6-fluorobenzimidazole, S-carboxybenzimidazole, 7-carboxybenzimidazole, S-carbethoxybenzimidazole,7-carbethoxybenzimidazole, S-sulphamylbenzimidazole, or 5-N-ethylsulphamylbenzimidazole, S-ethylsulphonylbenzimidazole and5-trifluoromethylsulphonylbenzirnidazole;

fall]a RI/4 R I 5 u x- R's u wherein:

A stands for monomethine or trimethine including substituted monomethineor trimethine,

each of R -R and R R" (the same or different) has one of the meaningsgiven for R R X -has the same significance as X,.

X 'has the same meaning as X,',

A has the same meaning as A each of m and p (the same or different)stands for one or two, and

each of Z and Z (the same or difi'erent) stands for the atoms necessaryto complete a heterocyclic nucleus of the thiazole, benzothiazole,naphthothiazole, thionamhtheno[7,6- d]thiazole, thiadiazole, oxazole,benzoxazole, naphthoxazole, selenazole, benzoselenazole,naphthoselenazole, 2-quinoline, 4-quinoline, pyrimidine, quinoxaline,quinazoline, 2-pyridine, 3,3-dialkylindolenine or of the benzimidazoleseries,

representative examples of these heterocyclic nuclei can be found abovein the definition of Z in formula I.

The dyestuffs corresponding to the above general formulae can beprepared according to the methods known by those skilled in the art ofrnethine dye chemistry.

According to a further embodiment of the invention, the recordingmaterial contains one or more substances that increase thephotoconductivity of the recording material in the inherent spectralsensitivity range of the said heterocyclic organic photoconductivecompounds. As already has been said a binding agent or a curing agentcan act as a sensitizing agent that enhances the total sensitivity ofthe recording element. In that respect are to be mentioned compoundscontaining one or more electron-attracting atoms or groups e.g. thecompounds according to the structural formula of the Belgian Pat.Specification No. 734,141 filed June 6, 1969 by Gevaert-Agfa N.V.Particularly suited are chlorine-containing compounds and the chlorinecontaining polymers of Table IV, and curing agents containing epoxygroups such as the tetraglycidyl ether of tetraphenylene-ethane.

Further have to be mentioned electromagnetic radiationsensitivediazonium salts that on exposure to electromagnetic radiation produce(a) radical(s) that irreversibly increase(s) the electroconductivity ofthe recording layer. Such substances as well as details about theirincorporation into a recording layer containing an organic polymericphotoconductive insulating substance are described in the UK. Pat.Specification No. 964,872 filed Apr. 22, 1959 by Gevaert Photo-ProductenN.V. and the US. Pat. No. 3,113,022 of Paul Maria Cassiers, Jean MarieNys, Jozef Frans Willems and Rene Maurice Hart, issued Dec. 3, 1963. Aparticularly suitable conductivity-increasing diazonium compound ispnitrobenzene-diazonium chloride. The diazonium compounds are preferablyused in an amount of 0.01 to 10 percent by weight in respect of the saidphotoconductive heterocyclic organic compounds.

Other additives well known in the art of preparing coatings forrecording purposes may be used, e.g. matting agents, fluorescingcompounds, phosphors, optical brightening agents, agents controlling theadhesive power of the recording layer, agents controlling theelasticity, the plasticity and the hardness of the recording layer,agents controlling the viscosity of the coating composition,antioxidants, gloss-improving agents, etc.

Transparent and semi-transparent recording materials containing thephotoconductive heterocyclic organic compounds as described hereinbeforeare especially suited for use in recording materials applied for thereproduction of microfilm images. Microfilm images can be copied incontact or enlarged optically on recording materials according to thepresent invention. According to the type of development, thetransparencies obtained (contact copies and enlargements) can serve asnegative or positive intermediate print for further printing, e.g. ondiazotype materials.

The semitransparent recording materials according to the presentinvention preferably have an optical density not larger than 0.30towards visible light or the copying light used in the printingapparatus wherein it is used as intermediate print.

The photoconductive heterocyclic organic compounds describedhereinbefore are further especially suited for being applied in themanufacture of pigment images wherein the latter may have the propertiesof a fluorescent compound or phosphor. As is generally known luminescentphosphors are used in screens of cathode-ray tubes and more particularlyin television, X-ray, radar and oscilloscope screens.

In color television screens phosphors of different color have to befixed on a screen in a particular pattern.

The described photoconductive compounds are successfully used in aprocess for the production of color television screens as described inthe French Pat. Specification No. 1,336,499 filed Sept. 26, 1962 byCompagnie Francaise Thomson Houston. According to the process describedin said specification a pattern of a phosphor on a screen-support isproduced by the steps of applying to said support a coating of anelectroconductive material and to said coating a layer comprising avaporizable or thermolysable photoconductive compound optionallyincorporated in a vaporizable or thermolysable binding agent. On saidcoating an electrostatic charge pattern corresponding with the pigmentpattern to be produced is formed in an electrophotographic way, and theelectrostatic charge pattern is developed with non-volatile powderparticles that have the desired phosphorescent or luminescentproperties. Subsequently the photoconductive layer containing thephosphor powder image is heated in order to remove the volatilesubstances of the photoconductive recording layer and to make thephosphor pattern adhere to the screen support.

In order to fix the powder image before applying the heating step it ispreferably overcoated with a layer of a thennolysable binding agent.

According to said French patent specification photoconductors of thegroup of anthracene, anthraquinone and xanthone are used. The recordinglayer may further contain boric acid.

The photoconductors mentioned in the French patent specification areadvantageously partly or wholly substituted by the photoconductivesubstances applied according to the present invention.

Suitable thennolysable binding agents belong to the class of thepolyacrylic acid esters and polymethacrylic acid esters e.g. polymethylmethacrylate, polyethyl methacrylate and polyethyl acrylate.

The thickness of the photoconductive layers is not critical but is opento choice within a wide range according to require ments in eachindividual case. Good results are attained with photoconductive layersof a thickness between 1 and 20 p.

preferably between 3 and .1.. Too thin layers do not have a sufficientinsulating power, in the absence of active electromagnetic radiationwhereas too thick layers require extensive exposure times.

In the manufacture of electrophotographic recording materials accordingto the present invention, a relatively conductive support for therecording layer is used, e.g. an electroconductive sheet or plate, or aninsulating sheet or plate covered with an electroconductive interlayer.Under electroconductive plate or sheet is understood a plate or sheetwhose electrical resistivity is smaller than that of the non-irradiated(dark-adapted) photoconductive layer i.e. in general smaller than10ohm/cm and preferably is at least 100 times as small as that of therecording layer. Supports whose resistivity is not higher than 10 ohm/cmare preferred. The recording layers itself have preferably an electricalinsulating power as high as possible without affecting too much thephotosensitivity by means of a too high amount of insulating bindingagent. Preferably the recording layers have in non-irradiated state(dark adapted state) a resistivity of at least 10 ohm/cm.

Suitable conductive plates are, e.g., plates of metals such as aluminum,zinc, copper, tin, iron, or lead.

Suitable electroconductive interlayers for insulating supports are,e.g., vacuum-coated metal and conductive metal compound (metal oxide ormetal salt) layers such as silver, tin aluminum, titanium dioxide andcopper iodide conductive layers, transparent conductive polymer layers,e.g. applied from polymers containing quaternized nitrogen atoms, suchas those described in the UK. Pat. Specification No. 950,960 filed Sept.23, 1960 by Gevaert Photo-Producten N.V. or layers containing conductiveparticles, e.g. carbon black and metal particles dispersed in a binder.The binder used for said particles has a resistivity preferably lowerthan 10 ohm/cm. A suitable binder for that purpose is gelatin,

It is possible to produce transparent photoconductive recordingmaterials by applying the photoconductive compounds together with asuitable binder- (if necessary) from a clear solution to a conductivetransparent base or a transparent insulating base coated with anelectroconductive transparent interlayer.

As transparent bases resin sheets having an optical density of not morethan 0.10 are preferred, e.g., a sheet made of polyethyleneterephthalate or cellulose triacetate. The conductive interlayerpreferably consists-of a metal coating, e.g., a vacuum-coated aluminiumlayer having an optical density of not more than 0.30 or of a conductivetransparentpolymer layer composed, e.g., of an organic polyionicpolymer, e.g. a polymer containing quaternized nitrogen atoms such as aquaternized polyethylene-imine.

In reproduction techniques wherein the prints are to be produced on anopaque background preferably a paper sheet is used as support for therecording layer.

Paper sheets that have an insufficient electrical conductivity arecoated or impregnated with substances enhancing their conductivity, e.g.by means of a conductive overcoat such as a metal sheet laminatedthereto.

As substances suited for enchancing the conductivity of a paper sheetand which can be applied in the paper mass are Paper sheets arepreferably impermeabilized to organic solvents, e.g. by means of awater-soluble colloid or by strongly hydrating the cellulose fibers suchas in the case of glassine p l ectrophotographic materials according tothe present invention can be used in any of the difierent techniquesknown in recording with the aid of photoconductors. According to apreferred embodiment they are used in a technique based on the dischargeof an electrostatically charged recording layer by exposure to light.

Photoconductive recording materials prepared according to the presentinvention can be used in exposure units equiped with incandescent lamps,so that they neednot be exposed with light rays rich in ultraviolet suchas those emitted by a high-pressure mercury vapor bulb.

The electrostatic charging of photoconductive recording elementsaccording to the present invention can be efiected according to anymethod known in electrophotography, e.g. by friction with a smoothmaterial, with a material possessing a high electric resistance, e.g. acylinder coated with polystyrene, by corona discharge, by contactcharge, or by discharge of a capacitor.

Recording materials containing the said organic photoconductivesubstances can be used in a recording technique comprising a negativecorona charging as well as in a recording technique comprising apositive corona charging.

In order to obtain an electrostatic image, it is possible to effect thecharging and exposure steps simultaneously and even to expose therecording layer image-wise before charging since a conductivity image isformed that is not destroyed immediately, especially if diazonium saltsare used in the recording element. It is preferred, however, that thecharging is effected before image-wise exposure.

The electrostatic latent image can be converted into a visible imageeither on the electrophotographic material wherein the latent image wasformed, or on a material to which the electrostatic latent image wastransferred, e.g. by application of the method described in the BelgianPat. Specification No. 529,234 filed May 29, 1954 by BattelleDevelopment Co.

The conversion of the original or transferred latent image into avisible image can occur according to one of the techniques known inelectrophotography, wherein use is made of a conductivity pattern (e.g.electrolysis) or the electrostatic attraction or repulsion of finelydivided colored substances, which, e.g. are present in a powder mixture,in an electrically insulating liquid (e.g. in the form of a suspension)or in a gas (e.g. in the form of an aerosol), or wherein electrostaticattraction is used for selectively wetting charged portions of therecording layer, as described in the U.K. Patent Specification Nos.1,020,505 filed Nov. 8, 1961 and 1,033,419 filed Nov. 26, 1962 both byGevaert Photo-Producten N.V.

When the sign of the charge of the developing powder or developingliquid is properly chosen, either a negative or a positive print can beobtained from any original. If both printing material and developingpowder or developing liquid have the same sign of charge, the powderonly adheres to the discharged areas so that a negative print isobtained. If the signs of the recording material and of the developingpowder particularly mentioned hygroscopic compounds and antistatic 01'de pi g l q i fi' a po i p in is Obtainedagents as described, e.g., inthe U.K. Pat. Specification No. 964,877 filed May 2, 1960 by GevaertPhoto-Producten N.V., and antistatic agents of polyionic type, e.g.CALGON CON- DUCTIVE POLYMER 261 (registered trademark of CalgonCorporation, lnc., Pittsburgh, Pa., USA. for a solution containing 39.1percent by weight of active conductive solids, and which contain aconductive polymer having recurring units of the following type:

If a colored powder is used for making visible the latent image, thevisible image obtained can, if necessary, be fixed according to one ofthe methods known in electrophotography, e.g. by heating, or it can betransferred to another support, e.g. according to the method describedin the UK. Pat. Specification No. 658,699 filed Apr. 14, 1949 byBattelle Memorial Institute, and fixed thereon.

The said heterocyclic (Iganic photoconductive compounds can also beapplied in a thermoplastic recording process to form a ripple-image asdescribed, e.g., in the UK. Pat. Specification No. 964,881 filed May 17,1960 by Gevaert Photo- BEEF?" -Y;

Evidently, the present inventionby no r rieans is limited to one orother particular embodiment of using the electrophotographic materialcontaining the photoconductive compounds as described herein. Theexposure technique the charging method, the formation of the chargepattern, the transfer of such pattern if applied, the developing method,and the fixation or the transfer of the developing material pattern maybe modified or adapted.

The composition of the recording materials used in these methods may beadapted to the requirements of the recording process used.

Electrophotographic materials according to the present invention can beemployed in reproduction techniques, wherein different kinds ofelectromagnetic radiations are used, e.g. visible light, U.V. light,X-rays and 'y-rays.

In order to prepare an electrophotographic material according to thepresent invention various techniques may be applied.

In practice, the photoconductive substances involved, either alone ortogether with other additives such as those described above, preferablyare first dissolved or dispersed in a suitable organic solvent such as aketone, e.g. acetone, chlorinated hydrocarbons, e.g. methylene chloride,and aliphatic esters, e.g. ethyl acetate, or in a mixture of two or moreof such solvents. The solution or dispersion thus obtained is uniformlyspread on a surface of a suitable support, e.g. by centrifuging,spraying, brushing, or coating. Thereupon the layer formed is dried insuch a way that a solid photoconductive layer is formed on the surfaceof the support.

With regard to the structure of the photoconductive compounds usedaccording to the present invention we do not limit said compounds to theparticular atoms and groups that have been indicated already for thevalue of the bivalent substituent X. Indeed, X may be any atom or grouphaving an electronegative character with respect to the carbon atom ofthe quinoline nucleus to hich it is attached in the 2- or 4- position.So, in addition to the atoms and groups already mentioned we includealso e.g. for the meaning of X each group introduced by means of anactive methylene compound and wherein the carbon atom of the activemethylene compound becomes double bonded to the quinoline nucleus in theX substituent position, For example the group wherein each of Q and Qrepresents an electronegative substituent e.g. a cyano group, an arylgroup an acyl group e.g. a benzoyl group, a carboxylic ester group, anamide group or a substituted amide group, or Q and Q represent thenecessary atoms to close a heterocyclic ring having an electronegan'vecharacter e. g. a pyrazolone-S nucleus, In that respect are particularlymentioned the following groups in the meaning of X:

Groups of that type are generally known from merocyanine dye chemistryand can be introduced in a carbonyl group containing compound e.g.according to a preparation technique described in the UK. Pat.Specification No. 869,138 filed July 11, 1957 by Gevaert Photo-ProductenNV. and are examplified as suitable substituents in photoconductivecompounds in the US. Pat. No. 3,041,165 of Oskar Siis, Kurt-WalterKliipfel, Wilhelm Neugebauer, Martha Tomanek and Hans Behmenburg issuedJune 26, 1962. The following examples lllustrate the present invention.

EXAMPLE ll To a polyethylene terephthalate support of p. a conductivetransparent coating was applied from an aqueous solution of gelatin andCALGON CONDUCI'IVE POLYMER 261 (trade name) in a weight ratio of 2:1.Coating was carried out in such a way that the dried coating contained 2g of gelatin per sq. m. The electrical resistivity of the coating was lX 10 ohms per sq. cm.

An electrophotographic recording material was prepared by coating ontosaid conductive layer a solution containing:

Cop01y(vinyl chloride/vinyl acetate/maleic anhydride)(mol 5 g.

ratio: 86.5/13.3/0.2). Methylene chloride 100ml.

The solution was applied in such a ratio that the dried recording layercontained 3 g per sq. m. of said quinolin-Z-one compound asphotoconductor.

After a negative corona charging with a potential difi'erence of 6,000 Vbetween the corona wires and the ground, the charged recording layer wascontact-exposed for 5 sec. through a positive transparency of a testchart with incandescent bulbs that together represent 100 watts and wereplaced at a distance of 30 cm.

After exposure the development was carried out with a triboelectricallycharged positive toner on the base of three parts by weight of pitch,four parts by weight of colophony and three parts by weight of carbonblack.

A contrasty transparent positive copy of the transparency was obtained.

Analogous results as obtained with said quinolin-Z-one compound wereobtained with same amounts of heterocyclic organic photoconductivesubstances having the following structural formulae tautomeric structureof C O 0 CZH5 tautomer'lc structure of 0n applying a positive coronacharging with a potential difference of +6,000 V between the coronawires and the ground the exposure time lasted only 3 sec. to obtain agood image with the developer described in Example 4 hereinafter.

EXAMPLE 2 To an aluminum laminated paper a solution containing:

l-ethyl-3-phenyl-7-diethylamino-2-( l H)- quinolone 7.5 g.1,2-dichloroethane 100 ml. copoly(vinyl chloride/vinyl acetate/maleicanhydride) (mol ratio 86.5/13.3/0.2) 5 g.

l-ethyl-3-phenyl-7-diethylarnino-2-( 1H) quinolone 7.5 g. Rhodamine B(C.l. Basic Violet Cl.

The dried recording layer contained also 2.5 g of l-ethyl-3-phenyl-7-diethylamino-2-( 1H )quinolone per sq. m.

Each of the coated samples (A) and (B) was negatively charged with anegative corona having a potential difl'erence of 6,000 V between thecorona wires and the ground.

The sample (A) was contact-exposed for sec. at a distance of 25 cmthrough a step wedge having 0.30 log exposure increments by means of anOSRAM L 40 watt A 70 fluorescent tube having an emission maximum at 365nm.

The sample (B) was contact-exposed for a same period of time at adistance of 25 cm through a step wedge having 0.30 log exposureincrements by means of a tungsten filament lamp exposing the recordinglayer with 2,400 lux and having a color temperature of 2,600 K.

The latent wedge images were electrophoretically developed and contrastycopies were obtained. The electrophoretic developer used in thedevelopment was obtained by diluting the concentrated developercomposition described hereinafter in a volume ratio of l5/ 1 ,000 bymeans of ISOPAR l-I (trade name for an isoparafiinic hydrocarbon mixturehaving a boiling range of l77l 88 C sold by Esso Belgium, N.V., Antwerp,Belgium):

carbon black (average particle size nm) 30 g. zinc monotridecylphosphate as dispersing agent l.5 g. *lSOPAR H (trade name) 750 ml.resin solution prepared as described hereinafter 150 g.

EXAMPLE 3 To a glassine paper of 60 g per sq. m. the following solutionwas applied:

l-ethyl-3-phenyl-7-diethylamino-2( 1H)- quinolone 7.5 g.

FORMVAR 1595 E (a trade name for a polyvinylformal marketed byShawinigan Resins Corporation, Springfield Mass, U.S.A.) 5 g.

As spectral sensitizing agent: Orange Astrazon R (0.1. Basic Orange 22;C.l. 48,040) having 0.020 g.

the following structural formula:

l a N 7 ll 01- I CCH=CH -CCH Acetone 75 ml.

The solution was applied at such a rate that the dried recording layercontained 2 g of l-ethyl-3-phenyl-7- diethylamino-2(lH)-quinolone persq. m.

After a negative corona charging with a potential difierence of 6,000 Vbetween the corona wires and the ground, the charged recording layer wascontact-exposed for 3 see. through a positive transparency of a testchart with incandescent bulbs that together represent watts and wereplaced at a distance of 30 cm.

After the exposure the development was carried out with atriboelectrically charged positive toner on the base of three parts byweight of pitch, four parts by weight of colophony and three parts byweight of carbon black.

A constrasty positive copy of the transparency was obtained.

On adapting the exposure intensity analogous results were obtained witheach of the compounds exemplified in the Tables I, II and Ill.

EXAMPLE 4 Example 3 was repeated with the diflerence, however, that therecording layer was positively corona-charged with a corona potentialdifference of +6,000 V between the corona wires and the ground.

The positively charged recording layer was exposed for 1 sec. through atest chart by means of tungsten filament lamps irradiating the recordinglayer with 1,400 lux.

The positive charge image on the exposed recording layer waselectrophoretically developed with a developer obtained by diluting theconcentrated developer composition described hereinafter in a volumeratio of 15/ l ,000 by means of SHELL- SOL T (trade name for ahydrocarbon solvent marketed by Shell, Belgium, having a boiling rangeof 175-200 C, specific gravity at 15 C: 0.764, viscosity at 25 C: 1.62centipoise, flash point (Pensky-Martens) open cup: 71 C closed cup: 53C) Kauri-butanol number: 31 ASTM norm D 1,133 54 carbon black (averageparticle size 20 nm) 30 g. lecithine 1.5 g. SHELLSOL T (trade name) 750m1.

resin solution prepared as described hereinafter g.

The resin binder solution was prepared by heating at 60 C 500 g ofALKYDAL L 67 (trade name of Farbenfabriken Bayer A.G., Leverkusen, W.Germany for a linseed oilmodified (67 percent by weight alkyd resin))and 500 cc. of white spirit containing 1 1 percent by weight of aromaticcompounds till a clear solution was obtained, and subsequent cooling.

An image with high detail reproduction was obtained.

EXAMPLE 5 A solution of 4 g of l-ethyl-3-phenyl-7dimethylamino-2-(lH)-quinolone and 5 g of copoly( vinyl chloride/vinyl acetate/maleicanhydride)(mole ratio 865/] 3.3/0.2) in a mixture of 50 ml of methylenechloride and 50 ml of acetone was prepared. A sample of thisunsensitized photoconductor composition was coated at a ran'o of 2 g ofphotoconductor per sq. m. on a sheet of aluminum foil laminated to apaper support.

Other samples of the unsensitized coating composition were sensitized byaddition of 0.05 g of the sensitizing compounds mentioned in Table V andcoated in the same way asthe unsensitized sample.

Each of the coated samples was negatively charged with a negative coronahaving a potential ditference of 6,000 V between the corona wires andthe ground and then exposed for 15 sec. with 2,000 lux emitted by meansof an incandescent lamp placed at a distance of 25 cm through a stepwedge having 0.20 log exposure increments between consecutive steps.

The latent wedge images were electrophoretically developed by means ofan electrophoretic developer obtained by diluting the concentrateddeveloper composition described hereinafter in a volume ratio of 15/1,000 by means of the hydrocarbon solvent SHELLSOL T (trade name):

carbon black (average particle size 20 mu) 30 g. zinc monotridecylphosphate 1.5 g. SHELLSOL T (trade name) 750 ml. resin solution preparedas described hereinafter 150 g.

The resin binder solution was prepared by heating 500 g of ALKYDAL L 67(trade name of Farbenfabriken Bayer A.G., Leverkusen, W. Germany for alinseed oil (67 percent by weight)modified alkyd resin) and 500 ml ofwhite spirit containing ll percent by weight of aromatic compounds at 60C till a clear solution was obtained, and subsequent cooling.

Relative speed values of the developed samples were calculated based ona comparison of the number of visible steps in the wedge images obtainedin the sensitized photoconductor materials with the number of visiblesteps produced in an unsensitized coating, given a relative speed of100. The visible steps are the area of the wedge image that correspondwith the discharge area on exposure.

The following Table V lists the relative speed values for thesecoatings.

TABLE V Sensitizing compound Relative speed number 7 none 100 l 1700 2250 3 160 4 250 5 1700 6 160 7 160 8 160 9 160 10 250 11 250 12 4200 131000 14 4200 +N\ g I O1 CCH=CH J CHa CH3 S S \C-CH=CHCH=C/ i ll Br OCH;S S e CH 8 \?=CHE=C/ \O--CH= CH=C/S a O N 0= L .L .l

( 1 Hz-CH=CH zHs O O CH2 I omsor CH= CH= M N HO O C I 5 c1- Y H502 /CgH5N- it v 0 H 0: 2 5

CzHs

S Se

IL N

m-Q-coon 11. CzH

s mo 0 I c-oH=o-cH=o Hz 0H;

CzHz.

CH= CH=C O; I l

E OCH; H300 N l N I \\C C/ IL CH CH g EXAMPLE 61-ethyl-3-phenyl-7-diethylamino-2-( 1H)- quinolone 7.5 g. copoly(vinylchloride/vinyl acetate/maleie anhydride)(mol ratio: 86.5/l3.3/0.2) 5 g.

photoconductive zinc oxide powder prepared by oxidation of zinc vapour 4g. acetone 100 ml.

of organic photoconductor per sq. m.

After a negative corona charging with a potential difference of 6,000 Vbetween the corona wires and the ground, the recording layer was contactexposed for 5 sec. through a transparent test chart original with a highpressure mercury vapor lamp of 80 watts mainly emitting in theultraviolet wavelength range of the spectrum and being placed at adistance of 25 cm of the recording layer.

The electrophoretic development was carried out as described in Example5.

A sharp and contrasty semitransparent copy of the original was obtained.

EXAMPLE 7 To an aluminum-laminated paper a solution was appliedcontaining:

l-ethyl-3-phenyl-7-diethylamino-quinoline-Z- The coating proceeded insuch a way that the dried recording layer contained 2.5 g ofphotoconductive compound per The obtained recording material wasnegatively coronacharged with a corona-charging apparatus having apotential difference of -6,000 V between the corona wires and theground. Thereupon it was contact-exposed for 45 sec. at a distance of 30cm through a step wedge having 0.20 log exposure increments using 5OSRAM L 20 WHO fluorescent tubes mainly emitting in the UV. range andthe shorter wavelengths of the visible spectrum (OSRAM is a trade name).

After the exposure the development was carried out as described inExample 2.

A contrasty opaque positive copy of the step wedge was obtained.

EXAMPLE 8 Example 7 was repeated by using, however, as binding agentMOWlLITl-l 20 (trade name for a polyvinyl acetate marketed by FarbwerkeHoechst A.G., Frankfurt (M) Hochst, W. Germany). The same amounts ofpolymer and solvent were applied as in Example 7, the solvent, however,now being acetone.

Exposure and processing as described in Example 7 yielded the same imageresult.

EXAMPLE 9 To a polyethylene terephthalate support of 100 p. a conductivetransparent coating was applied from an aqueous solution of gelatin andCALGON CONDUCTIVE POLYMER 261 (trade name) in a weight ratio of 2:1. Thecoating was carried out in such a way that the dried coating contained 2g of gelatin per sq. m. The electrical resistivity of the coating was 1X 10 ohms per sq. cm.

An electrophotographic recording material was prepared by coating ontosaid conductive layer a solution containing:

CzHs

As chemical sensitizing agent:

Copoly viny1 cholride/vinyl acetate/maleic anhydride) (mol 5g.

ratio: 86.5/l3.3/0.2). Methylenechloride ml.

The solution was applied in such a ratio that the dried recording layercontained 2 g per sq. m of said quinoline2- one compound asphotoconductor.

After a negative corona charging with a potential difference of 6,000 Vbetween the corona wires and the ground, the charged recording layer wascontact-exposed for 7 sec. through a positive transparency of a testchart with incandescent bulbs that together represent l00 watts and wereplaced at a distance of 30 cm.

After the exposure the development was carried out as described inExample 2.

A contrasty transparent positive copy of the original was obtained.

EXAMPLE 10 A solution of 5 g of l-ethyl-3-phenyl-7-diethylamino-2-(lH)-quinolone and 5 g of copoly(vinylchloride/vinylace tate/maleicanhydride) (mole ratio 86.5/l3.3/0.2) in a mixture of 100 ml ofmethylene chloride was prepared.

A sample of this unsensitized photoconductor composition was coated in aratio of 2 g of photoconductor per sq. m on a sheet of aluminum foillaminated to a paper support.

Other samples of the unsensitized coating composition were sensitized byaddition of 0.2 g of the sensitizing compounds mentioned in Table VI andcoated in the same way as the unsensitized sample.

Each of the coated samples was negatively charged with a negative coronahaving a potential difference of 6,000 V between the corona wires andthe ground and then exposed for 30 see. with 1,400 lux emitted by meansof an incandescent lamp placed at a distance of 25 cm through a stepwedge having 0.20 log exposure increments between consecutive steps.

The latent wedge images were electrophoretically developed by means ofthe electrophoretic developer described in Example 5.

Relative speed values of the developed samples were calculated based ona comparison of the number of visible steps in the wedge images obtainedin the sensitized photoconductor materials with the number of visiblesteps produced in an unsensitized coating, given a relative speed of100. The visible steps are the area of the wedge image that correspondwith the discharged area on exposure.

The following Table VI lists the relative speed values for thesecoatings.

2. A recording process according to claim 1, wherein a pattern ofincreased conductivity is produced image-wise in a photoconductiveinsulating recording element comprising a photoconductive quinolinecompound carrying an oxygen atom in the two-position.
 2. exposing therecording layer to activating electromagnetic radiation creating anelectrostatic charge pattern corresponding with the phosphor pattern tobe formed,
 3. developing the electrostatic charge pattern by means ofphosphor particles, and
 3. A recording process according to claim 1,wherein a pattern of increased conductivity is produced image-wise in aphotoconductive insulating recording element comprising aphotoconductive quinoline compound carrying a sulphur atom in thetwo-position.
 4. A recording process, according to claim 1, wherein apattern of increased conductivity is produced image-wise in aphotoconductive insulating recording element comprising aphotoconductive quinoline compound carrying a group in the two-position.4. removing the photoconductive compound and optionally present bindingagent by heating the support.
 5. A recording process according to claim1, wherein a pattern of increased conductivity is produced image-wise ina photoconductive insulating recording element comprising aphotoconductive quinoline compound carrying in the two-position an iminogroup substituted with a phenyl group.
 6. A recording process accordingto claim 1, wherein a pattern of increased conductivity is producedimage-wise in a photoconductive insulating recording element comprisinga photoconductive quinoline compound carrying in the two-position anoxime group.
 7. A recording process according to claim 1, wherein apattern of increased conductivity is produced image-wise in aphotoconductive insulating recording element comprising aphotoconductive quinoline compound carrying in the two-position ahydrazone group.
 8. A recording process according to claim 1, wherein apattern of increased conductivity is produced image-wise in aphotoconductive insulating recording element comprising aphotoconductive quinoline compound carrying an oxygen atom in thefour-position.
 9. A recording process according to claim 1, wherein apattern of increased conductivity is produced image-wise in aphotoconductive insulating recording element comprising aphotoconductive quinoline compound carrying a sulphur atom in thefour-position.
 10. A recording process, according to claim 1, wherein apattern of increased conductivity is produced image-wise in aphotoconductive insulating recording element comprising aphotoconductive quinoline compound carrying in the four-position agroup.
 11. A recording process according to claim 1, wherein a patternof increased conductivity is produced image-wise in a photoconductiveinsulating recording element comprising a photoconductive quinolinecompound carrying in the four-position an imino group substituted with aphenyl group.
 12. A recording process according to claim 1, wherein apattern of increased conductivity is produced image-wise in aphotoconductive insulating recording element comprising aphotoconductive quinoline compound carrying in the four-position anoxime group.
 13. A recording process according to claim 1, wherein apattern of increased conductivity is produced image-wise in aphotoconductive insulating recording element comprising aphotoconductive quinoline compound carrying in the four-position ahydrazone group.
 14. A method for recording information according toclaim 1, comprising the steps of electrostatically charging andinformation-wise exposing the recording element to electromagneticradiation, thereby increasing the conductivity of the radiation struckareas and carrying off the electrostatic charge in said areas, anddeveloping the resulting electrostatic Pg,77 charge pattern by means ofan electrostatically attractable material.
 15. A recording materialcomprising a photoconductive insulating recording element capable ofbeing electrostatically charged in the absence of activatingelectromagnetic radiation and capable of retaining the applied chargefor a period of time long enough to produce thereon a developedelectrostatic charge pattern, carried on a layer or support of lowerresistivity and characterized in that said recording element contains atleast 10 percent by weight of a photoconductive compound correspondingto one of the following general formula:
 16. A recording materialaccording to claim 15, wherein said layer or support has a resistivityat least 102 as low as that of the recording element itself.
 17. Arecording material according to claim 15, wherein the support is a papersupport.
 18. A recording material according to claim 15, wherein thesupport is an insulating transparent resin support coated with atransparent electroconductive interlayer.
 19. A recording materialaccording to claim 15, wherein said binder is a polymer.
 20. A recordingmaterial according to claim 19, wherein said binder is ahalogen-containing polymer.
 21. A recording material according to claim20, wherein the halogen-containing polymer contains vinyl chlorideunits.
 22. A recording material according to claim 15, wherein thephotoconductive compound is used in admixture with a spectralsensitizing agent increasing the photosensitivity of the recordingelement.
 23. A recording material according to claim 15, wherein thephotoconductive compound is used in admixture with a spectralsensitizing dye.
 24. A recording material according to claim 15, whereinthe photoconductive compound is used in admixture with a photoconductivecompound selected from the group of photoconductive selenium, and thephotoconductive oxides, sulphides, and selenides of zinc, cadmium,mercury, antimony, bismuth and lead.
 25. A recording material accordingto claim 15, wherein the photoconductive recording element has anoptical density not higher than 0.30 for substantially visible light.26. A recording material according to claim 23, wherein the said dye isa triarylmethane dye, xanthene dye or a methine dye.
 27. A recordingmaterial according to claim 15, wherein the recording element contains7-dialkylamino-quinoline-2-one compound.
 28. A recording materialaccording to claim 15, wherein the photoconductive compound is1-ethyl-3-phenyl-7-diethylamino-2-(1H)-quinolone or1-ethyl-3-phenyl-7-dimethylamino-2(1H)-quinolone.
 29. A recordingmaterial according to claim 15 suitable for use in anelectrophotographic process, and wherein the recording element is asolid layer having a dark-resistivity of at least 108 ohm/cm.
 30. In animproved process for the production of a phosphor pattern on acathode-ray tube screen the improvement wherein said phosphor patterncontains a photoconductive compound corresponding to one of thefollowing general formula:
 31. A process according to claim 30, whereinthe phosphor pattern before heating is fixed with a thermolyzablepolymer layer or coating.
 32. A process according to claim 31, whereinthe polymer forming said layer or coating is a polyacrylic aCid ester orpolymethacrylic acid ester.
 33. The process of claim 1 wherein saidphotoconductive compound is1-ethyl-3-phenyl-7-diethylamino-2(1H)-quinolone or1-ethyl-3-phenyl-7-dimethylamino-2(1H)-quinolone.